Long before you became a part of your community and, hopefully, a contributing member of society, there were the original communities, which were made of networks of bacteria. The inhabitants of these worked together to ensure the survival of as many members as possible. Today, these communities are called biofilms and they’re found almost anywhere they can survive. Fossil records indicate they’re at least 3.25 billion years old, and they’ve been with us ever since.[1]

What Are Biofilms?

Biofilms are slimy, microbial strongholds that grow in aqueous environments and typically adhere to surfaces. If you’ve ever taken a microbiology lab, you’ve probably seen sticky glue-like substances grow in Petri dishes after performing a smear. The small slimy colonies smeared on plates are biofilms. They’re inhabited by tiny individual microbial colonies of bacteria, yeast, or algae. Outside the lab, the types of surfaces biofilms stick to range from the interior of sink pipes to boat hulls, the exterior of rocks and leaves, and even areas of the body like your teeth and tissues. Some well-known examples you might be familiar with include pond scum, mildew, kombucha SCOBYs, and dental plaque.

Biofilms help ensure the survival of the various microscopic organism species that they’re composed of by decreasing their chances of being removed or eliminated by soaps, antiseptic detergents, and antibiotics. Usually, only the surface or edges of the biofilm are affected, protecting the deeper layers of microorganisms and slime from removal. This presents a health concern if the biofilm contains harmful microorganisms. In fact, some researchers believe that some persistent or recurring infections may result from stubborn biofilms in the body that evade immune defenses.[2]

Biofilms aren’t all bad, though. Beneficial biofilms in your gut provide a stable colony of probiotic bacterial and fungal species that prevent harmful colonies from gaining a foothold in your gut ecosystem. Biofilms develop in the appendix, mouth, vagina, colon, ear canals, lungs, and nasal passages. Despite being a seemingly dry tissue, your skin harbors a community of S. epidermidis in a biofilm structure found throughout the outer layers of your epidermis.[3]

How Do Biofilms Form?

The microorganisms most people are familiar with are planktonic, or free floating, organisms. The formation of a biofilm usually begins when a single planktonic microbe tenuously clings to a surface. In the body, this typically means a given microbe finds a molecular handhold called an adhesion site on a surface (epithelial) cell of one of your tissues or organs, but microbes can also cling to the mucous layer that covers certain tissues. From here, other microbes begin linking to the original.[4]

This small collection of microorganisms forms a settlement on the surface by secreting a substance called extracellular polymeric substance (EPS), which is made of enzymes, DNA, proteins, and sugar molecules called polysaccharides. It’s kind of like microbial terraforming. They make your body a more hospitable environment for more microbial cells and act as a sort of spider’s web, preventing microbial cells from dislodging from the matrix. Notably, these colonies are more slime than cells. Only about 15% of a given biofilm is made up of cells. The remaining 85% is comprised of the slimy EPS matrix.[3]

This network of microbes and slime develops channels to transport nutrients and water to the microcolonies embedded within it, much like how the blood vessels in your body supply your cells with nutrients. These cells almost function as an organ by communicating with each other using the slimy matrix to deliver chemical messenger molecules, a mechanism called quorum sensing. This chemical communication leads to gene regulation, in which genes are activated and inactivated as needed to preserve the biofilm or help it grow.[3, 5]

Just like the mildew in your shower, biofilms grow. They form a stronger hold on their surface, making them more difficult to wipe out. This is an excellent characteristic for health-promoting biofilms, but it’s alarming when harmful microbes plant their flag in your body to start settling down.

Healthy Biofilms in the Gut

Your gut is uniquely suited to biofilm formation since the lining of the intestine is covered with a mucous gel-layer that protects your gut microbes. Gut microbes can infiltrate this layer to set up stable colonies. Notably, microbes are rarely able to fully breach the protective mucous layers throughout your body to reach the underlying epithelial cells. In the gut, your immune system appears to encourage biofilm formation by secreting immunoglobulin A (IgA), an immune protein that makes bacteria stick together, or agglutinate. This phenomenon encourages stable microbial composition and inhibits the growth of harmful organisms.[3, 6, 7]

Some researchers think that intestinal biofilms are another line of intestinal defense. They simultaneously assist the development of biofilms, but also prevent microorganisms and undesirable substances and molecules from crossing into the body from the colon. You can think of them as a sort of sealant that protects a potentially porous tissue from being infiltrated, like a wood varnish that seals out water to prevent mildew.[8]

Biofilms Harmful to Your Health

Unfortunately, biofilms and the mucous layers they assimilate with also protect harmful microbes from being eliminated. In fact, a harmful gut ecosystem might be more challenging to balance because the mucous layer that coats the intestines tends to thicken to defend your surface cells from inflammation-provoking substances, foods, drugs, and microbes. This gives the unhealthy microbes a larger mucous layer in which to proliferate. The microbes huddle down, guarded by their biofilm matrix, to weather whatever immune defenses your body tries.[2]

The Effects of Harmful Biofilms

Harmful biofilms protect harmful organisms from physical removal, immune activity, antimicrobials, and antibiotics. Not only do they allow unchecked harmful organism overgrowth, but they also impede the development of health-promoting biofilms. In the presence of harmful biofilms, there is potential for increased virulence due to gene transfer between cells in the biofilm.

Biofilms have proven frustratingly resistant to efforts to thwart or address organism overgrowth. They are especially worrying for people with cystic fibrosis and chronic sinus infections due to the great quantities of mucus generated that can quickly become a safe harbor for harmful microbes.[2]

An Example of Harmful Biofilm: Dental Plaque

One easily observed biofilm is found right in your mouth. Dental plaque is a biofilm that tends to harbor acid-producing microbial species. If you don’t remove it regularly by brushing, flossing consistently, and seeing the dentist, the acid these microbes produce can damage your teeth. Poor dental hygiene leads to bad breath, tooth decay, dental cavities, and gum disease. It may also contribute to the incidence and severity of respiratory conditions in people with weak immune systems when biofilm is transferred from the mouth to the lungs.[9, 10]

Although you can’t sterilize your teeth, you can physically remove oral biofilms, yeast, and bacteria by brushing and flossing after every meal. Eliminate sticky candies, refined sugar, and refined carbs from your diet to discourage the harmful bacteria like Streptococcus mutans from dominating your mouth microbiota. These kinds of food cling to your teeth and feed harmful oral bacteria. Stay hydrated to prevent dry mouth, a condition that also contributes to stable harmful colonies.[9]

Going even further, you can try to nourish helpful oral bacteria growth like Streptococcus salivarius by eating fermented foods, probiotics, and cutting down on the alcohol-based mouthwashes which indiscriminately wipe out both healthy and harmful oral microbes.

How to Encourage Healthy Biofilms

Biofilms can occur almost anywhere that microorganisms live on your body. Therefore, it’s essential to promote healthy biofilms in the gut and reduce your chances of developing harmful biofilms in other areas of the body with good (but not excessive) hygiene, a strong immune system, and a healthy diet. Managing biofilms in your body often requires actions specific to the tissue or area, like brushing your teeth. Consult your healthcare practitioner if you suspect harmful biofilms may be affecting your health.

Research is still emerging for solutions to biofilms in difficult to reach tissues, so there aren’t any hard and fast recommendations to address them. That said, aromatic phytochemicals like thymol, eugenol, carvacrol, and cymene have distinct biofilm-inhibiting properties, and they’re easy to incorporate into your diet.

Consume herbs and spices like thyme, oregano, and cloves to get these beneficial phytochemicals, along with many conutrients like terpenes, into your diet. You can consume the oils of these spices by adding a tiny drop to a pot of fragrant tea or a large jar of homemade salad dressing. Look to your food first to preserve your health. Relying on a diverse health-promoting diet provides you with a complementary array of active phytonutrients that offer a multi-pronged approach to keep you in excellent health.[11, 12, 13, 14]